Flow of dielectric particles in a fluid sample tested by a microfluidic chip is primarily controlled by interaction of dielectrophoresis force and alternating voltage electroosmosis force.
Applicant's Taiwanese Patent No. I507803 discloses a dielectric particle controlling chip and a method of manufacturing the same. The dielectric particle controlling chip includes a chip body, a first interdigitated electrode disposed on the chip body, a second interdigitated electrode disposed on the chip body and spaced apart from the first interdigitated electrode, and a dielectric layer disposed securely on the chip body and covering the first and second interdigitated electrodes. The dielectric layer is used to increase the alternating voltage electroosmosis force and reduce the dielectrophoresis force so as to enhance flow of the dielectric particles in the controlling chip and concentration of the dielectric particles at specific areas of the controlling chip for subsequent detection.
However, the dielectric layer of the dielectric particle controlling chip is made from a photoresist material, such as SU-8 photoresist. The thickness of the dielectric layer is as high as about 1200 nm, which results in a relatively far distance between the dielectric particles in the fluid sample and the interdigitatedelectrodes. Therefore, a relatively high voltage input of at least 40 Vpp and a relatively high driving voltage frequency of at least 1000 Hz are required to drive the flow of the dielectric particles in the controlling chip and the concentration of the dielectric particles at specific areas of the controlling chip.